Fabrication Process And Characteristics Of Silicon-based Resistive Random Access Memory With High κ Dielectric

Semiconductor logic devices and memory devices are two of the most important parts in the integrated circuits. In recent years, the feature size of semiconductor memory device has been scaled below 30 nm with the development of integrated circuit technology. Meanwhile, it is also accompanied with new problems about material, structure, and physics. For the purposes of improving the memory device performance and finding the alternatives instead of dynamic random access memory and flash memory, so far many new devices have been investigated all over the world including ferroelectric memory, magnetoresistive memory, phase-change memory and resistance random access memory (RRAM). Among them, RRAM has attracted very wide interests due to its advantages on simple structure, fast P/E speed, low power consumption and good compatibility with conventional CMOS technology.Now the main problem of RRAM investigation is the conduction mechanism. RRAM may use different kinds of material and structures so that the characteristics may be also different, so various kinds of conduction mechanism model are proposed. However, there still lacks of a universal model that can instruct the device exploitation and improvement. In addition, it is recently found that there exists a rectifying effect in RRAM, which is very important for the device application and useful to simplify the circuit structure. But now we know little of the relationship between mechanism of the rectifying effect and device structure. Thirdly, the optimization of the device structure and characteristics, and the device reliability are of great importance for the device application, which should be further investigated.Against the RRAM key issues, the thesis has studied the fabrication process and device characteristics of silicon-based RRAM with high k dielectric, which includes conduction mechanism, rectifying characteristics, temperature characteristics, area characteristics, noise characteristics and structure optimization. The points are shown:(1) RRAM samples were fabricated with different areas, various high k dielectric material and metal electrodes. (2) The samples were electrically measured and analyzed. The characteristics included Set/Reset characteristics, Ⅰ-Ⅴ characteristics,1/f noise and random telegraph noise characteristics. (3) A new RRAM conduction mechanism model was proposed as well as a the related equivalent resistance model. Then a corresponding RRAM energy band diagram was demonstrated by comparing the experimental results with the model.The innovative points of the thesis are that:(1) It is found that the total RRAM resistance is constituted of semiconductor/dielectric contact resistance, dielectric resistance and dielectric/metal contact resistance in series. On the different conditions or resistance states, each resistance has a different influence on Ⅰ-Ⅴ characteristics. (2) When analyzing the RRAM conduction mechanism, it is found that phonons can assist electronic transport. Based on the phonon assisted model, all experimental data can be explained very well. (3) With the equivalent resistance model and phonon assisted model, the rectifying characteristics of silicon-based RRAM with high k dielectric can be explained in a natural way. (4) Random telegraph noise and 1/f noise characteristics have been measured in large quantity and the experimental data are discussed in detail. The above results are of great significance for insight into RRAM conduction mechanism, instruction to the improvement and optimization of device structure and characterisitics and promotion of RRAM exploitation and application.